On Thu, Jul 24, 2014 at 08:37:32PM -0400, Pranith Kumar wrote:
> This commit checks the return value of the zalloc_cpumask_var() used for
> allocating cpumask for rcu_nocb_mask.
>
> Signed-off-by: Pranith Kumar <[email protected]>
Hmmm... I saw the check in the previous patch, but didn't see removal
of the later have_rcu_nocb_mask check. Please see below.
Thanx, Paul
> ---
> v2: no change from v1
>
> kernel/rcu/tree_plugin.h | 23 ++++++++++++-----------
> 1 file changed, 12 insertions(+), 11 deletions(-)
>
> diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
> index 520538a..9c9a01c 100644
> --- a/kernel/rcu/tree_plugin.h
> +++ b/kernel/rcu/tree_plugin.h
> @@ -54,7 +54,10 @@ static void __init rcu_bootup_announce_oddness_nocb(void)
> {
> #ifndef CONFIG_RCU_NOCB_CPU_NONE
> if (!have_rcu_nocb_mask) {
> - zalloc_cpumask_var(&rcu_nocb_mask, GFP_KERNEL);
> + if (!zalloc_cpumask_var(&rcu_nocb_mask, GFP_KERNEL)) {
> + pr_info("rcu_nocb_mask allocation failed\n");
> + return;
> + }
> have_rcu_nocb_mask = true;
> }
> #ifdef CONFIG_RCU_NOCB_CPU_ZERO
> @@ -66,17 +69,15 @@ static void __init rcu_bootup_announce_oddness_nocb(void)
> cpumask_copy(rcu_nocb_mask, cpu_possible_mask);
> #endif /* #ifdef CONFIG_RCU_NOCB_CPU_ALL */
> #endif /* #ifndef CONFIG_RCU_NOCB_CPU_NONE */
> - if (have_rcu_nocb_mask) {
> - if (!cpumask_subset(rcu_nocb_mask, cpu_possible_mask)) {
> - pr_info("\tNote: kernel parameter 'rcu_nocbs=' contains
> nonexistent CPUs.\n");
> - cpumask_and(rcu_nocb_mask, cpu_possible_mask,
> - rcu_nocb_mask);
> - }
> - cpulist_scnprintf(nocb_buf, sizeof(nocb_buf), rcu_nocb_mask);
> - pr_info("\tOffload RCU callbacks from CPUs: %s.\n", nocb_buf);
> - if (rcu_nocb_poll)
> - pr_info("\tPoll for callbacks from no-CBs CPUs.\n");
> + if (!cpumask_subset(rcu_nocb_mask, cpu_possible_mask)) {
What happens if CONFIG_RCU_NOCB_CPU_NONE=y and the rcu_nocbs= boot
parameter is not specified and we get here?
In order to get visible failures when testing, build with
CONFIG_CPUMASK_OFFSTACK=y.
> + pr_info("\tNote: kernel parameter 'rcu_nocbs=' contains
> nonexistent CPUs.\n");
> + cpumask_and(rcu_nocb_mask, cpu_possible_mask,
> + rcu_nocb_mask);
> }
> + cpulist_scnprintf(nocb_buf, sizeof(nocb_buf), rcu_nocb_mask);
> + pr_info("\tOffload RCU callbacks from CPUs: %s.\n", nocb_buf);
> + if (rcu_nocb_poll)
> + pr_info("\tPoll for callbacks from no-CBs CPUs.\n");
> }
>
> /*
> --
> 2.0.1
>
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